Input-sequencing arrangements for multi-point recorders



Aug. 6, 1968 K. B. PARKER, JR

INPUT-SEQUENCING ARRANGEMENTS FOR MULTI-POINT RECORDERS 3 Sheets-.Sheet 1 Filed March 1,

INPUT-SEQUENCING ARRANGEMENTS FOR MULTI-POINT RECORDERS 3 Sheets-Sheet 2 mmomoowm Filed March 1, 1967 1968 K. B. PARKER, JR 3,396,404

INPUT-SEQUENCING ARRANGEMENTS FOR MULTI-POINT RECORDERS Filed March 1, 1967 5 Sheets-Sheet 5 United States Patent 3,396,404 INPUT-SEQUENCING ARRANGEMENTS FOR MULTI-POINT RECORDERS Kenneth B. Parker, Jr., Norristown, Pa., assignor to Leeds & Northrup Company, Philadelphia, Pa., a

corporation of Pennsylvania Filed Mar. 1, 1967, Ser. No. 619,679 Claims. (Cl. 346-34) ABSTRACT OF THE DISCLOSURE An electromechanical sequencing arrangement including a rotary multi-position switch, a transfer switch having actuating mechanism coupled to the rotary switch, a multi-pole relay, and auxiliary circuitry including a diode and auxiliary relay means of either electromagnetic or solid-state type, cooperating with the rotary and transfer switches in control of energization of the multi-pole relay.

CROSS-REFERENCE TO RELATED APPLICATIONS The sequencing arrangements disclosed are improvements upon that shown in copending Paschkis application Ser. No. 457,609, filed May 21, 1965, now Patent No. 3,317,913.

BACKGROUND OF THE INVENTION (1) Field of the invention.-The presently contemplated use of the invention is in connection with multipoint recorders whose input-selector switch has fewer points than the number of input-circuits.

(2) Description of prior art.With prior sequencing arrangements, such as shown for example in the aforesaid Paschkis application, there is, in practice and despite close tolerances in manufacture and adjustment, an inevitable mismatch between the transitions of the switch which effects transfers from one to another group of input relays and the transitions from the last to first position of the rotary selector switch. Such mismatch has given rise to many problems including incorrect identification of an input under measurement, improper energization of alarm and/or control circuits, premature introduction of samples to be analyzed, erratic balancing action of the recorder, and improper mixing of samples intended to be individually analyzed. By costly precise manufacture and critical adjustment of components some of these problems have been solved.

SUMMARY OF THE INVENTION In accordance with the present invention, all of these problems are solved by an auxiliary circuit means which temporarily suspends the shift, demanded by a change in state of the transfer switch, from one to another group of input relays until the rotary selector switch leaves its last position to begin the next revolution.

More particularly, the fixed contacts of the rotary switch are respectively connected to the poles of a multipole relay having its normally-closed contacts respectively connected to one group of input relays: and having its normally-open contacts respectively connected to another group of input relays: for alarm and/or control purposes, each of the input relays may be paralleled by one or more other load devices. The energization state of the multi-pole relay is determined by the transfer Patented Aug. 6, 1968 ice switch which changes its state from open-to-closed in one revolution of the rotary switch and from closed-to-open in a following revolution, the transitions in state of the transfer switch each occurring at non-critical time in a period for which the rotary switch is in its last position of a revolution. However, the change in energization state of the relay called for by a change in state of the transfer switch does not occur until the rotary contact structure of the selector switch leaves its last position of a revolution because of the provision of the aforesaid auxiliary circuit means.

In one preferred embodiment of the invention, the auxiliary circuit means includes a second relay and a diode. The second relay is energized when said rotary selector switch is in its last position and its normallyclosed contacts complete a first energization circuit, via the closed transfer switch, for the multi-pole relay. The diode is connected to the normally-open contacts of the last pole of the multi-pole relay to provide a second energization circuit for the multi-pole relay.

In another preferred embodiment of the invention, the functions of the aforesaid second relay are performed by solid-state circuitry including a normally ON transistor set to its OFF state when the selector switch is in its last position and then completing the aforesaid energization circuit of the multi-pole relay if the transfer switch is closed.

In both of said preferred embodiments, the diode is poled to preclude out-of-sequence energization of one of the input relays via the first energization path of the multi-pole relay.

The invention further resides in an electromechanical sequencing arrangement having features hereinafter described and claimed.

For a more detailed understanding of the invention, reference is made to the following description and to the accompanying drawings.

Brief description of drawings FIGS. 1 and 2 schematically illustrate the components and circuitry of the aforesaid two preferred sequencing arrangements; and

FIGS. 3A, 3B, 4A, 4B are explanatory figures referred to in discussion of actuating mechanism for the transfer switch of FIGS. 1 and 2.

Description of preferred embodiments Referring to FIG. 1, the movable contact 99 of the multi-position switch 97 is rotated, as for example by recorder means later herein briefly described, to engage the angularly-spaced stationary contacts 100 in repeating sequence. In the particular arrangement shown in FIG. 1, the contacts 100 of rotary switch 97 are twelve in number and are respectively connected to the movable contacts of the double-throw switches Nos. 1-12 formed by the 12-pole contact assembly of the electromagnetic switch of relay 190. The normally-closed front contacts of poles Nos. 1-12 are respectively in series with the load devices K1K12 and the normally-open back contacts of poles Nos. 1-12 are respectively in series with the load devices K13-K24.

With switch 24 left open to inhibit energization of relay 190, the load devices Kl-KIZ are in turn energized and deenergized in each of the successive revolutions of the rotary sequencing switch 97.

With switch 24 closed, the circuitry for controlling the energization of relay 190 provides for sequential energization of the load devices Kl-K12 for a first revolution of switch 97, sequential energization of load devices K13- K24 for the next or second revolution of switch 97, sequential energizationof load devices K1-K12 for the next or third revolution, and so on, i.e., the sequential energization of load devices Iii-K24 repeats for every two successive revolutions of switch 97. Specifically and for purposes fully explained in the aforesaid copending application Ser. No. 457,609, the load devices Kl-K24 are input relays of a multi-point recorder.

In FIG. 1, there are two circuits for controlling energization of the main relay 190: one circuit includes the diode 120 and the other includes transfer switch 200 and the normally-closed contacts 121 of the auxiliary relay 122. For the indicated poling of the current supply source 123, the cathode of diode 120 is connected to the positive terminal of the coil of relay 190 and its anode is con nected to the normally-open back contact of pole No. 12 of relay 190. The coil of the auxiliary relay 122 is connected between the negative terminal of the supply source 123 and the movable contact of the No. 12 pole of relay 190. The auxiliary relay contacts 121, switch 24 and transfer switch 200 are connected in series between the positive terminals of supply source 123 and the coil of relay 190. The operating means 124 for the transfer switch 200 is mechanically coupled to the rotary sequencing switch 97 to effect closure of switch 200 while switch 97 is in its No. 12 position for one revolution, to effect opening of switch 200 while switch 97 is in its No. 12 position for the next revolution, to effect re-closure of switch 200 while switch 97 is in its No. 12 position for the following or third revolution, and so on; i.e., this opening and closing sequence of switch 200 repeats for every two revolutions of the rotary switch 97.

For purposes of explanation, it is now assumed that switch 24 has been closed for the sequential operation of the 24-input relays K1-K24 and that transfer switch 200 is open. Under these conditions, the main relay 190 is not energized and the input relays or load devices Kl-Kll are in turn energized via the normally-closed front contacts of poles 1 to 11 of relay 190 as the rotary switch 97 moves through its first 11 positions. When switch 97 moves to its No. 12 position, it energizes the load device K12 through the normally-closed front contacts of the No. 12 pole of main relay 190, and in addition energizes the auxiliary relay 122 with resultant opening of contacts 121 of the auxiliary relay.

Before the contact 99 of rotary switch leaves its No. 12 position, the transfer switch 200 is closed by its actuating means 124. However, closure of transfer switch 200 is not effective at this time to energize main relay 190 because, as above mentioned, the contacts 121 of the auxiliary relay 122 are open.

When the contact 99 of rotary switch 97 leaves its No. 12 position to engage the next fixed contact 100 at the No. 1 position, the auxiliary relay 122 is deenergized. The resultant closure of contacts 121 of auxiliary relay 122 effects energization of relay 190 via closed transfer switch 290. Such energization of relay 190 effects closure of the normally-open back contacts of its poles Nos. 1-12 so that now with the rotary switch 97 in its No. 1 position, the load device K13, rather than load device K1, is energized. It is to be noted that diode 120 is so poled that the energization of main relay 190 does not result in concurrent energization of load device K24.

As switch 97 continues to rotate through its Nos. 2-11 positions, the load devices K14 to K23 are energized in sequence via the closed back contacts of poles Nos. 211 of the main relay 190 which has remained energized via closed transfer switch 200 and the normally-closed contacts 121 of the auxiliary relay 122. When rotary switch 97 arrives at its No. 12 position, both the load device 24 and the auxiliary relay 122 are energized. The resultant opening of the auxiliary relay contacts 121 breaks the circuit between the transfer switch 200 and the coil of main relay 190, but the main relay remains energized via the path afforded by diode 120, the closed back contacts of the No. 12 pole of relay 190 and the rotary switch 97 in its No. 12 position.

Before rotary switch 97 leaves its No. 12 position, the transfer switch 200 is opened by its mechanical operating means 124. Thus, when rotary switch 97 leaves its No. 12 position, the energization circuit for main relay 190 via diode is broken, whereupon the contacts of all poles Nos. 1-12 of relay 190 return to the normal position shown in FIG. 1. The energization circuit for the auxiliary relay 122 through switch 97 is also broken when switch 97 leaves its No. 12 position, but it is to be noted that the closure of contacts 121 of the now deenergized relay 122 does not result in energization of the main relay 190 at this time because the transfer switch 200 is open. With the main relay 190 deenergized, the re-arrival of rotary switch 97 at its No. 1 position now results in energization of the load device K1 for beginning of the next two-revolution sequential actuation of load devices Kl-K24 by the 12-position rotary switch 97.

It is to be noted that because of the position of auxiliary relay 122 and diode 120, both the closure of transfer switch 200 for transition from the first sequence (Kl- K12) to the second sequence (K13-K24) and the opening of transfer switch 200 for transition from the second sequence (K13-K24) back to the first sequence (K1- K12) may occur at any time while the rotary switch 97 is in its No. 12 or last position of each sequence because in both cases the change in the energization state of the main relay 190 is triggered by the transfer of rotary switch 97 from its No. 12 to its No. 1 position. Except for such auxiliary relay 122 and diode 120, the circuitry of FIG. 1 is similar to that shown in FIG. 10 of aforesaid copending application Ser. No. 457,609, but in absence of those elements it is necessary that the transfer switch 200 operate at the precise instant the rotary switch 97 moves to its No. 1 position in order to effect a clean transfor from input relay K12 to K13 and from input relay K24 to K1. Such exact synchronism between rotary switch 97 and transfer switch 200 not only required precise mechanical adjustment, but also required precise symmetry of the actuating mechanism 124 to insure that opening and closure of transfer switch 200 occur in exact relationship. These problems have been solved by the circuitry shown in FIG. 1 and by the equivalent solid-state circuitry shown in FIG. 2 and now described.

As in FIG. 1, the diode 120 of FIG. 2 poled as shown is connected from the positive side of the coil of main relay to the normally-open back contact of the No. 12 pole of that relay and serves the same purposes as in FIG. 1. The reversely poled diode 216 connected across the coil of relay 190 is provided to protect any of the contacts involved in the deenergization of relay 190 from the induction voltage and resultant destructive arcing at said contacts upon cutoff of its current, and may be used in the circuit of FIG. 1.

The transistors 217, 218 are in replacement of auxiliary relay 122 of FIG. 1 and serve the purposes of auxiliary relay 122 and its normally-closed contacts 121. The base of transistor 217 is connected through resistor 219 to the movable contact of the No. 12 pole of relay 190 and is also connected through resistor 220 to the negative terminal of current source 123. The emitter of transistor 217 is connected to the negative terminal of current source 123 through diode 221 poled a shown and is also connected to the positive terminal of current source 123 through resistor 222. The collector of transistor 217 is connected to the base of transistor 218 and thence through resistor 223 to the positive terminal of current source 123. The emitter of transistor 218 is connected, in series, with diode 224, transfer switch 200 and switch 24 to the positive terminal of the coil of main relay 190. Suitable circuit parameters are given in Table A below.

TableA Transistor:

217 2N3053 218 2N3053 Diode:

120 1N816 216 1N816 221 1N816 224 1N816 Resistor:

219 kilohms 220 do 6.8 222 do 47 223 ohms 560 For purposes of explanation, it is now assumed that switch 24 has been closed for the 2.4 input-relay sequence and that transfer switch 200 is open. Under these conditions, the main relay 190 is not energized, and as before described in discussion of FIG. 1, the input relays Kl-Kll are in turn energized via the normally-closed front contacts of relay poles Nos. 1-11 as the rotary switch 97 moves through its corresponding positions. When movable contact 99 of switch 97 arrives at its No. 12 position, it energizes input relay K12 through the normally-closed front contacts of the No. 12 pole of relay 190, and in addition applies a positive signal to the base of transistor 217. Transistor 217 is thus switched to its ON or full conductive state and remains so until the rotary switch 97 moves from its No. 12 position.

Before the movable contact 99 of rotary switch 97 leaves its No. 12 position, the transfer switch 200 is closed by its actuating mechanism 124. However, the closure of switch 200 is not effective at this time to Operate main relay 190 because with transistor 217 in its ON state, the voltage drop through resistor 223 to the base of transistor 218 is such that the transistor 218 is effectively OFF, its emitter current being insuflicient to pull in the relay 190.

When movable contact 99 of rotary switch 97 leaves its No. 12 position, the positive signal is removed from the base of transistor 217 with consequent switching of transistor 217 to the OFF state. With transistor 217 switched OFF, the voltage applied to the base of transistor 218 rises to a positive value for which transistor 218 is fully ON, so to effect pull-in energization of main relay 190 via the closed transfer switch 200. Such energization of relay 190, as in the system of FIG. 1, effects closure of the normally-open back contacts of its poles Nos. 112 so that now with rotary switch 97 in its No. 1 position, the input relay K13, rather than input relay K1, is energized. Also again as in FIG. 1, it is to be noted that diode 120 is so poled that the energization of relay 190 does not result in concurrent energization of input relay As switch 97 continues to rotate through its Nos. 2-11 positions, the input relays K14-K23 are energized in turn via the closed back contacts of poles Nos. 2-11 of relay 190 which has remained energized via the closed transfer switch 200 and the ON transistor 218. When rotary switch 97 arrives at its No. 12 position, the input relay K24 is energized via the closed back contacts of the No. 12 pole of relay 190. Although the transistor 217 is again switched ON, and in turn switches OFF the transistor 218, the coil of relay 190 remains energized via the path now afforded by diode 120, the closed back contacts of No. 12 pole of relay 190 and the rotary switch 97 in its No. 12 contact position.

Before rotary switch 97 leaves its No. 12 position, the transfer switch 200 is opened by its mechanical operating means 124. Thus, when rotary switch 97 leaves its No. 12 position, the energization circuit for relay 190 through diode 120 is broken, whereupon the contacts of all poles Nos. 1-12 of the relay 190 return to the normal position shown in FIG. 2. The ON bias of transistor 21-7 is also removed, but the resultant ON state basebias of transistor 218 does not result in energization of relay 190 at this time because the transfer switch 200 in the emitter circuit of transistor 218 is open. With main relay 190 deenergized, the re-arrival of rotary switch at its No. 1 position now results in energization of input relay K1 for beginning of the next two-revolution sequential actuation of input relays K1-K12 by the 12-position rotary switch 97. With the circuitry of FIG. 2, in which the transistors 217, 218 form the functions of the auxiliary relay 122 of FIG. 1, both the closure of transfer switch 200 for transition from the first sequence (relays Kl-K12) to the second sequence (relays K13K24) and the opening of transfer switch 200 for transition from the second sequence (relays K13-K24) back to the first sequence (K1K12) may occur at any time while the rotary switch 97 is in its No. 12 position for each sequence, because in both cases the change in energization state of the main relay 190is triggered by the transfer of rotary switch 97 from its No. 12 position to its No. 1 position. It is not necessary that the actuating mechanism 124 of the transfer switch be precisely constructed or adjusted to insure opening and closing of switch 200 at the precise instant that rotary switch 97 moves to its No. 1 position in successive revolutions to insure a clean positive transfer from input relay K12 to input relay K13 and from input relay K24 to input relay K1.

In FIGS. 1 and 2, the components of the actuating mechanism 124 of the transfer switch 200 are identified by the same reference characters as in the aforesaid copending application Ser. No. 457,609 to which reference may be made should a detailed description of its construction and operation be desired. An abbreviated description is here given in the following discussion of FIGS. 3A, 33, 4A and 4B.

The cams 201, 202, rotatable in unison with gear of the drive means for rotary switch 97 (FIGS, 1, 2), respectively individually control the angular position of cam-follower plates 203, 204 with respect to their common axis as provided by a fixed stud shaft. Cam 201 is of circular perimeter eccentric to its axis of rotation and is received by the forked end 206' of cam-follower plate 203. Cam 202 has two base radii having a single high point 199 and is engaged by the pawls 207, 208 of calmfollower plate 204.

A small permanent magnet 215 is adjustably fastened to leg 209 of a plate 204. When plate 204 is moved counterclockwise to a position for which magnet 215 is sufficiently close to the magnetic reed of switch 200, the normally-open contacts of switch 200 move to closedcircuit position. Conversely, when plate 204 is swung clockwise away from switch 200, the magnet 215 releases the contacts of switch 200 for movement to open-circuit position.

The upper end of spring 210- is looped over the upper ears 211, 212 of plates 203, 204 respectively and the lower end of spring 210 is looped under the lower ears 213, 214 of those plates. For each revolution of cam 201, the plate 203 makes a complete sine-wave cycle between the clockwise and counterclockwise limits of its motion to tension the spring 210. For each revolution of cam 202, the plate 204 abruptly moves to its clockwise limit position, remains there for a half-revolution of cam 202, abruptly moves to its counterclockwise limit positionand there remains for the next half-revolution of cam 202.

More particularly, for the angular position of c ams 201, 202 shown in FIG. 3A, the plate 203 is at the clockwise limit of its motion and the plate 204 is at the counterclockwise limit of its motion: the bias of spring 210 is applied between the upper ear 212 of plate 204 and the lower ear 213 of plate 203. Within the next few degrees of cam motion, the pawl 20$ rides off the high point 199 of cam 202 and the plate 204 is quickly swung by spring 210 to the clockwise limit of its motion (FIG. 3B). In consequence, the magnet 215 is abruptly pulled away from transfer switch 200 to open it.

For the angular position of cams 201, 202 shown in FIG. 4A, the plate 203 is at a counterclockwise limit of its motion and plate 204 is at a clockwise limit of its motion: the bias of spring 210 is now applied between the upper ear 211 of plate 203 and the lower ear 214 of plate 204. Within the next few degrees of cam rotation, the pawl 207 rides off the high point 199 of cam 202 and the plate 204 is abruptly swung by spring 210 to the counterclockwise limit of its travel (FIG. 4B). In consequence, the magnet 215 is quickly moved toward transfer switch 200 to close it.

With the circuitry of FIG. 1 or FIG. 2, it is not nec essary that the transfer switch 200 change its state precisely at 180-degree intervals because, as above stated,

the change in energization state of main relay 190 is triggered by movement of rotary switch 97 from its No.

12 position-not by the opening or closing of transfer switch 200. Precise timing of switch 200 is not necessary: it suffices that the actuating mechanism 124 opens and closes the transfer switch 200 at any time while the rotary switch 97 is in its last or No. 12 position. As schematically indicated in FIG. 1, the drive gears 105, 106 for effecting rotation of sequencing switch 97 and of cams 201, 202 of the transfer-switch actuating mechanism 124 may be elements of a multi-point recorder 9, and the load devices Kl-K24 may be input relays for sequentially connecting a corresponding group of condition-responsive transducers T1T24 to self-rebalancing measuring circuitry of the recorder. The chart motor of the recorder may provide the power for drive gears 105 and 106.

While the sequencing switch is in each of its contact positions, the print wheel 10 of the recorder 9 is moved transversely of the chart 18 by the recorder rebalancing mechanism (not shown) to a position corresponding with the response of the transducer then in circuit. After balance and before sequencing switch 97 moves to its next contact position, the print wheel 10' is moved into engagement with the continuously-driven recorder chart 13 to print a dot indicating the measured value and a numher or character identifying the measured point. The print wheel is rotated about its axis in synchronism with the sequencing switch 97, in turn to present toward chart 18 the point-identification symbols corresponding with the measuring points.

For a more detailed description of suitable mechanism and circuitry for effecting the various motions of print wheel 10, reference may be had to the aforesaid copending application Ser. No. 457,609.

What is claimed is:

1. An electromechanical sequencing arrangement comprising a multi-pole relay having a plurality of poles with normally-open and normally-closed contacts,

a multi-position switch having a series of fixed contacts respectively connected to corresponding poles of said relay and swept by rotary contact structure,

a transfer switch mechanically coupled to said multiposition switch and electrically connected to control the energization state of said multi-pole relay, the transitions from open-to-closed state of said transfer switch and the transitions from closed-to-open state of said transfer switch occurring in different revolutions of said rotary contact structure, each of said transitions occurring at non-critical time during the period of engagement between said rotary contact structure and the last fixed contact of said series, and

auxiliary circuit means effective throughout each of said periods temporarily to maintain the existing state of said multi-pole relay independently of the state of said transfer switch and to provide that the transition of said multi-pole relay from either one to the other of its energization states occurs when said rotary contact structure leaves the last contact of said series.

2. An electromechanical sequencing arrangement as in claim 1 comprising a second relay having normally-closed contact structure and energized at least during those periods in which occurs transition from open-to-closed state of said transfer switch to maintain said multi-pole relay in deenergized state until. said rotary contact structure leaves the last fixed contact of said series, and

means connected during those periods in which occurs transition from closed-to-open-state of said transfer switch to maintain said multi-pole relay in energized state until said rotary contact structure leaves the last fixed contact of said series.

3. An electromechanical sequencing arrangement as in claim 2 in which the last-named means includes a diode connected from the normally-open contacts of the last pole of said multipole relay to the coil thereof and poled to isolate those contacts when said multi-pole relay is energized via the closed transfer switch and the normallyclosed contacts of said second relay.

4. An electromechanical sequencing arrangement as in claim 1 in which the auxiliary circuit means comprises normally ON transistor means temporarily switched to OFF state upon engagement of said rotary contact structure with the last fixed contact of said series and effective for the closed state of said transfer switch to complete an energization circuit for said multi-pole relay, and

means for temporarily maintaining the energized state of said multi-pole relay after said transfer switch has opened until said rotary contact structure leaves the last fixed contact of said series.

5. An electromechanical sequencing arrangement as in claim 4 in which the last-named means includes a diode connected from the normally-open contacts of the last pole of said multi-pole relay to the coil thereof and poled to isolate those contacts when said multi-pole relay is energized via the closed transfer switch and said normally ON transistor means.

6. An input sequencing arrangement for a multi-point recorder comprising a multi-position switch having rotary contact structure which in each revolution sweeps the first to the last of a series of fixed contacts,

a multi-pole relay having a series of normally-closed contacts which for the deenergized state of the relay respectively connect a first group of input relays to said series of fixed contacts of said multi-position switch and having normally-open contacts which for the energized state of the relay respectively connect a second group of input relays to said series of fixed contacts of said multi-position switch,

a transfer switch for controlling the energization state of said multi-pole relay, the transitions from open-toclosed state of said transfer switch occurring in every other revolution of said multi-position switch during the period its said rotary contact structure is sweeping the last fixed contact of said series and the transitions from closed-to-open state of said transfer switch occurring in the intervening revolutions of said multi position switch during the period its said rotary contact structure is sweeping said last fixed contact of said series, and

auxiliary circuit means effective throughout said period in each revolution of said multi-position switch temporarily to maintain the existing state of said multipole relay despite change in state of said transfer switch so as to provide that change in state of said multi-pole relay occurs when the rotary contact structure of said multi-position switch leaves said last fixed contact of the series.

a second relay energized via said rotary contact structure during each of said periods and having normallyclosed contacts,

a first energization circuit for said multi-pole relay in- 7. An input sequencing arrangement for a multi-point recorder as in claim 6 in which the auxiliary circuit means comprises a second relay energized during said periods, the resultant position of contacts of said second relay temcluding said transfer switch and said normally-closed porarily suspending control of said multi-pole relay contacts of the second relay, and by said transfer switch, and a second energization circuit for said multi-pole relay a diode connected from the normally-open contacts of including a diode connected from the normallythe last pole of said rnulti-pole relay to the coil of open contacts of the last pole of said multi-pole relay said relay, said diode being so poled as to preclude 10 to its actuating coil, said diode being poled to preout-of-sequence energization of one of said input vent out-of sequence energization of the last input relays via the transfer switch and contacts of said relay of said second group via said first energization second relay. circuit of the multi-pole relay.

8. An input sequencing arrangement for a multi-point 10. An input sequencing arrangement for a multirecorder as in claim 6 in which the auxiliary circuit means point recorder comprising comprises a rnulti-position switch having rotary contact structure transistor means triggered to the OFF state during which in each revolution sweeps the first to the last said period of each revolution of said rotary conofaseries of fixed contacts, tact structure and triggered to the ON state as said a multi-pole relay which for its deenergized state conrotray contact structure leaves said last fixed contact meets a first group of input relays respectively to of the series then to effect energization of said multisaid series of fixed contacts and which for its enerpole relay if said transfer switch has been closed, gized state connects a second group of input relays and respectively to said series of fixed contacts,

a diode connected from the normally-open contacts of a transfer switch mechanically coupled to said multithe last pole of said multi-pole relay to the coil of said position switch, the transitions of said transfer switch relay temporarily to maintain continued energizafrom open-to-closed state and from closed-to-open tion of said relay despite opening of said transfer state occurring in alternate revolutions of said rotary switch and until said rotary contact structure leaves contact structure and each at non-critical time durthe last fixed contact of said series, said diode being ing the period said rotary contact structure is in enpoled to preclude out-of-sequence energization of gagement with said last contact of the series, one of said input relays via said transistor means and a normally ON transistor temporarily maintained in the transfer switch when they are respectively ON the OFF state during each of said periods, and closed. a first energization circuit for said multi-pole relay in- 9. An input sequencing arrangement for a multi-point cluding said transfer switch and said transistor, and

recorder comprising a second energization circuit for said multi-pole relay a multi-position switch having rotary contact structure including a diode connected from the normallywhich in each revolution sweeps the first to the last open contacts of the last pole of said multi-pole relay, ofaseries of fixed contacts, said diode being poled to prevent out-of-sequence a multi-pole relay which for its deenergized state conenergization of the last input relay of said second meets a first group of input relays respectively to said group via said first energization circuit of the multiseries of fixed contacts and which for its energized pole relay. state connects asecond group of input relays respec- References Cited tively to said series of fixed contacts,

a transfer switch mechanically coupled to said multi- UNITED STATES PATENTS position switch, the transitions of said transfer switch 3 317 913 5 19 7 P hki 345....34

from open-to-closed state and from closed-to-open state occurring in alternate revolutions of said rotary contact structure and each at non-critical time during the period said rotary contact structure is in engagement with said last contact of the series,

RICHARD B. WILKINSON, Primary Examiner.

J. W. HARTARY, Assistant Examiner. 

